CorpusHuman Anatomy
RespiratoryCartilage

Thyroid cartilage

Cartilago thyroidea

Also known as: Adam's apple, laryngeal prominence

The largest laryngeal cartilage: two quadrilateral laminae fused anteriorly to form the laryngeal prominence ("Adam's apple"), shielding the vocal folds.

Show on body map Respiratory Tract

Overview

The two laminae meet in the midline at an angle of ≈90° in men and ≈120° in women, so the laryngeal prominence is more conspicuous in men (it enlarges at puberty under testosterone, lengthening the vocal folds and deepening the voice). Above the prominence is the V-shaped superior thyroid notch. The posterior border of each lamina extends into a superior horn, attached to the greater horn of the hyoid by the lateral thyrohyoid ligament, and an inferior horn, which forms a synovial cricothyroid joint with the side of the cricoid. An oblique line on each lamina gives attachment to sternothyroid, thyrohyoid and the inferior constrictor.

The vocal ligaments, vestibular ligaments, thyroarytenoid muscles and the stalk of the epiglottis attach to the inner surface of the angle. Rocking of the thyroid on the cricoid at the cricothyroid joints (by cricothyroid) changes the distance between the thyroid angle and the arytenoids and so the tension of the vocal folds.

Location

Anterior neck at C4–C5, below the hyoid bone, above the cricoid cartilage.

Parts & subdivisions

  1. Laminae
    Two plates fused anteriorly.
  2. Laryngeal prominence and superior thyroid notch
    Palpable midline landmarks.
  3. Superior and inferior horns
    Superior horns attach to the hyoid; inferior horns articulate with the cricoid.
  4. Oblique line
    Muscle attachment on the external surface.

Anatomy

Articulations

Cricothyroid joints (synovial) between the inferior horns and the cricoid; suspended from the hyoid by the thyrohyoid membrane.

Ligaments

Thyrohyoid membrane (median and lateral thyrohyoid ligaments); thyro-epiglottic ligament; median cricothyroid ligament below.

Histology

Hyaline cartilage; begins to ossify in early adulthood (earlier and more extensively in men), which can mimic a foreign body on radiographs.

Function

  • Shields the vocal apparatus anteriorly.
  • Anchors the vocal and vestibular ligaments and the epiglottis.
  • Tilts on the cricoid (cricothyroid joint) to tense the vocal folds and raise pitch.

Clinical significance

Laryngeal trauma

Fracture of the thyroid cartilage (strangulation, direct blows) causes hoarseness, subcutaneous emphysema and airway compromise. A fractured superior horn or hyoid at autopsy suggests manual strangulation.

Surface landmark

Running a finger down from the laryngeal prominence leads to the cricothyroid membrane and then the cricoid — the key sequence for emergency airway access.

Compiled from standard anatomy and physiology references — see the Respiratory System sources. For education only; not medical advice.